There is extensive art on the polymerization of ethylene and higher alpha-olefins, including dienes, using Ziegler type catalysts containing either alkyl metals or alkyl metals in which an alkyl group has been replaced by X, OR, SR, NR.sub.2, etc., in combination with a transition metal compound of Groups IVB-VIII, where X=halide, and R=C.sub.1 to C.sub.20 hydrocarbyl substituent.
For the commercial stereospecific polymerization of propylene and higher alpha olefins, only a few alkyl metal compounds have been found effective in combination with titanium or vanadium chlorides. Commercially, only R.sub.2 AlCl or R.sub.3 Al are used together with a crystalline form of TiCl.sub.3 or TiCl.sub.3.nAlCl.sub.3. Mixtures of R.sub.3 Al and R.sub.2 AlCl and RAlCl.sub.2 are made in situ and have been disclosed as catalyst components frequently in the art. However, RAlCl.sub.2 is known to be a catalyst poison (A. Caunt, J. Polymer Sci. C4, 49 (1963).) R is preferably ethyl (Et) or isobutyl; N=0.01 to 0.75.
This inventor's U.S. Pat. No. 3,418,304 discloses a complex of alkyl metal compounds such as Et.sub.2 AlNEt.sub.2 and Lewis acid salts such as AlCl.sub.3 and MgCl.sub.2, e.g. Et.sub.2 AlNEt.sub.2.AlCl.sub.3 as cocatalysts to entirely replace conventional aluminum alkyls, but such complexes are entirely different from the concept of utilizing organomagnesium compounds in combination with a Group III metal alkyl compound as catalyst supplements for Ziegler systems employing Ti metal transition halide.
U.S. Pat. No. 3,638,897 teaches a catalyst system for the polymerization of alpha-olefins which includes a titanium compound, an alkyl aluminum halide compound, and a metal halide; however, this patent fails to recognize the use of an organomagnesium compound as an integral part of the catalyst system.